Over the last 15 years or so the use of foam dispensers based on aerosols using pressurized gas has declined steeply for environmental reasons. This has lead to the development of foaming dispensers that exploit a manual pumping action to blend air and liquid to create foam.
A particular category of such known dispensers, also known as foaming dispensers or foamers, provides both a liquid pump and an air pump mounted at the top of a container. The liquid pump has a liquid pump chamber defined between a liquid cylinder and a liquid piston, and the air pump has an air pump chamber defined between an air cylinder and an air piston. These components are typically arranged concentrically around a plunger axis of the pump. The liquid piston and air piston are reciprocal in their respective cylinders by the action of a pump plunger. Typically the two pistons are integrated with the plunger. An air inlet valve and a liquid inlet valve are provided for the air chamber and liquid chamber. An air discharge passage and a liquid discharge passage lead from the respective chambers to an outlet passage by way of a permeable foam-generating element, normally one or more mesh layers, through which the air and liquid pass as a mixture. Preferably the air discharge passage and liquid discharge passage meet in a mixing chamber or mixing region immediately upstream of the permeable foam-generating element.
Current designs of dispenser pumps do not allow for proper ventilation to the mating bottle in a pump and bottle system. The failure to achieve proper ventilation prevents vacuum build-up inside the mating liquid bottle as liquid is pumped out of the liquid bottle. In addition, current designs do not permit proper liquid sealing during shipment. Often, the liquid in the liquid bottles will leak out during transportation wasting the liquid and creating an undesirable mess.